illuminance
Sign in to savealt=Illuminance diagram with units and terminology.|thumb|372x372px|Illuminance diagram with units and terminology In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance.
Key facts
- Physical quantity.name
- Illuminance
- Physical quantity.unit
- lux
- Physical quantity.otherunits
- phot, foot-candle
- Physical quantity.baseunits
- cd·sr·m−2
- Physical quantity.dimension
- \mathsf{L}^{-2} \mathsf{J}
via Wikipedia infobox
Article
7 sectionsContents
- Common illuminance levels
- Astronomy
- Relation to luminous intensity
- Relation to luminance
- See also
- References
- External links
{{Infobox physical quantity | name = Illuminance | unit = lux | otherunits = phot, foot-candle | symbols = | baseunits = cd·sr·m−2 | dimension = \mathsf{L}^{-2} \mathsf{J} }} alt=Illuminance diagram with units and terminology.|thumb|372x372px|Illuminance diagram with units and terminology In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance.
In SI units illuminance is measured in lux (lx), or equivalently in lumens per square metre (lm·m−2). Luminous exitance is measured in lm·m−2 only, not lux. In the CGS system, the unit of illuminance is the phot, which is equal to . The foot-candle is a non-metric unit of illuminance that is used in photography.